Another small business has fallen victim to a fraudster going by the false name 'Simon Fraser' who posed as a member of NatWest staff in a bogus call from the bank - this time swiping £80,500 from the business account.

Charterhouse Accountants, based in Harrow, Middlesex, were duped in a repeat of a scam that This is Money has previously reported on. Once again, NatWest has insisted the fraud is the responsibility of the victim and refused to cover the losses.

On 24 April this year, Micky Ackenson, a partner at Charterhouse was forwarded a phone call by his staff from a man calling himself ‘Simon Fraser’ claiming to be from Bankline, the business banking service from NatWest.

Caught out: Charterhouse Accountants were duped out of £80k in yet another telephone fraud case

The fraudster told them about a suspicious payment, claiming £64,000 had been transferred to a Mrs J Stevenson in Aberdeen.

Both said they hadn’t made this payment. The fraudster then said Micky needed his smartcode reader for a refund.

Smartcode readers are now common security features and enable users use their banking debit to generate a code needed to make payments.

The pair were given a phone number they could call to confirm he was a member of Bankline staff, a tactic used to give confidence the call is genuine - the fraudster need only stay on the line without hanging up to continue speaking with the victim if they do choose to call the number.

In any event, Micky and David were now convinced and saw no need to call.

To help pull the wool over their eyes further, the voice on the phone began to list genuine transactions on their account, complete with the amounts involved. He also knew their overdraft limit.

The scammer then advised that, to refund the payment, he would require further security details. Now convinced the call was genuine, the pair handed over characters from the Pin and password as requested.

At this point, the fraudster said another £40,000 was being targeted.

As the con went on and on, the fraudster said he could refund the original £64,000, but would allow the genuine payments to go through, in order to not bring added nuisance to the firm.

Online fraud: 84% of small businesses believe they will never be a target for scammers

Micky was told to tap a number through his Bankline smartcode device and then read the number this then generated over the phone.

At this point, Micky became suspicious and called their NatWest accounts manager on another phone line.

The manager on the phone confirmed the phone number given earlier in the conversation was genuine. They then proceeded to give the code to the fraudster.

The NatWest manager – who remained on the other line – saw the payment going through on the system and realised 'Simon' was a fraudster.

Despite this, he couldn’t stop the payment going out. In all, £80,500 had been taken.

To Mickyand David's dismay, NatWest has refused to cover the losses.

In a letter, the bank said: ‘In this case your authorised Bankline users divulged security information, including user ID, Pin and password details and smartcard challenge code to an unknown third party over the telephone.

‘This is a breach of the security terms of use of Bankline and is what has caused the loss.’

However, David and Micky feel that the bank hasn’t investigated the case properly. It has requested IP addresses for anyone that accessed its Bankline accounts in previous six months and also a full log with timings of the movement of funds, which ended up in a Lloyds Bank account.

Six months down the line and NatWest haven’t revealed this information.

They also haven’t been told how the fraudster knew their overdraft limit and genuine pending transactions.

A spokesman from NatWest, said: ‘We know how distressing fraud can be for all involved and provide ongoing support to our customers to deal with the effects, which may include a refund or tracing the stolen money.

‘There is an extremely large number of sophisticated online scams affecting banking customer across the sector.

‘We work closely with the police and crime agencies to try and prevent this crime, and communicate frequently with our customers about our security measures and specific threats.

‘We will never ask customers for their password, pin, card details or security information either over the phone or when they log-in to the banking system online.

‘We recommend that our customers download the Trusteer Rapport security software. Customers should remember that these rules can protect them even if a Trojan or other virus has infected a computer.’

The bank added that money is typically moved to 'money mule' accounts and cashed out quickly or moved overseas, making it difficult to track.

It also confirmed that it has seen a handful of cases where the fraudster has called using the name of Fraser – but there are a variety of names used by those committing the scam.

Charterhouse cannot take the case to the Financial Ombudsman as the business is too large, employing 28 staff. The FOS will only rule on business cases when a company employs less than ten staff, or turnover is below £2million.

This is Money has campaigned in the past for better protection for small businesses who are more likely to be targeted by fraudsters, owing to the fact they tend to have bigger balances, overdraft limits and more payments going in and out.

Some victims have received efunds while some, like Charterhouse, are refused. RDS Transport lost £240,000 to online fraudsters and was initially refused compensation from NatWest at the end of 2013. It was facing axing 100 staff as a result, just before Christmas.

However, after This is Money intervention along with Treasury Select Committee member and MP, John Mann, the bank decided to refund the money.

Last month, anti-virus software developer Kaspersky Lab revealed that 82 per cent of businesses believe they would never be a target of fraud, while a third of firms would not know what to do if they had an IT security breach tomorrow.